Therapy using available antiretroviral agents (nucleoside analogue reverse transcriptase inhibitors AZT, ddl, ddC, and d4T), has proven relatively toxic and of limited efficacy. Gene therapy of HIV-1 infection offers great potential for long lasting benefits. Preliminary evidence indicates that protection and in vivo selection of peripheral blood CD4+ lymphocytes transduced ex vivo with vectors expressing hairpin ribozymes targeting HIV-1 is a realizable possibility, making this strategy an outstanding candidate for aggressive exploration and development. Arguments for proceeding directly to initial human trials are convincing. No gene therapeutic agent has been shown to be more potent or persistent in vitro than the hairpin ribozyme. The gene transfer technology to be used has been tested and found to be safe in clinical trials, including the same retroviral vector used in our preliminary studies. Toxicity testing in small animals has been performed, and no acute toxicity observed. Finally, as there is no reliable, proven animal model of HIV-1 pathogenesis, human trials are needed in order to obtain preliminary indications of efficacy. This project is designed to move innovative approaches into Phase I clinical trials with the greatest possible speed and safety, in such a manner as to gather the maximum amount of information concerning the safety and effects of ex vivo ribozyme gene therapy for HIV-1 infection, and to facilitate future studies targeting different cell populations, as well as plans to move directly to expanded Phase I/II clinical trials, should initial results prove promising. Objectives include: (1) Optimizing the safety and efficiency of transduction of CD8-depleted lymphocytes from HIV-1 seropositive individuals, (2) Administration of ribozyme and control vector tranduced autologous cells to HIV-1 infected human volunteers, (3) To assess the safety of this therapy, (4) To monitor the protective effects of ribozyme expression by comparing the in vivo survival of cells transduced with ribozyme expressing vectors to that of cells transduced control vector in a controlled fashion, and (5) To support additional Phase I protocols for evaluation of ribozyme gene therapy of HIV infection.